1. FIELD OF THE INVENTION
The invention concerns a non-return valve which is constituted by a body provided with an opening closed by a cover through which a non-return obturator can be mounted or demounted.
2. DESCRIPTION OF THE PRIOR ART
Known valves of this kind are well thought of despite certain disadvantages as they allow repairs or maintenance to be carried out without the need to remove the valve as access is available to the obturator by a route other than via the connections between the valve and the pipes between which it is connected.
In a first known type of valve the obturator is a flap hinged near the cover with the result that these valves are easy to manufacture but offer only mediocre performance in terms of sealing and hydraulic characteristics.
In a second type of known valve, for example from the document FR-A-2427532, the obturator is fastened to a coaxial rod which cooperates with a guide fitted to the valve body. These valves offer satisfactory performance in terms of sealing but they introduce a significant head loss and require a relatively complex valve body which is costly to manufacture, because to enable fitting of the rod into the guide on the body through the cover the obturator must be mobile along an axis transverse or inclined to the upstream-downstream axis with which the valve connectors are coaxial, that is to say the main axis of the pipe into which the valve is inserted.
A valve with an obturator of this same type is also known except that it is movable along the upstream-downstream axis, which is made possible by the fact that the rod guide means are carried by the cover only. This entails inserting the obturator transversely through the opening and then pivoting the obturator-cover assembly to fit the cover to the opening at the same time the obturator is placed on the upstream-downstream axis. Because of this arrangement of the obturator the valve has good hydraulic characteristics but its performance in terms of sealing is mediocre.
The invention is directed to providing a valve of the same kind but which is easy to manufacture, has good hydraulic characteristics and offers good performance in teams of sealing.